CMP-9264 Expose showLayoutBounds API on ComposePanel

This exposes a showLayoutBounds property on ComposePanel (desktop only)
that allows users to turn on or off the showLayoutBounds property on
the root layout node owner(s). It appears that the property only fully
takes effect after some interaction with the Compose UI, or a bounds
change, even though we call renderImmediately() in the property setter.

This might be a separate issue that is outside the scope of this change.

The change mostly makes a few private fields internal to allow piping
the property up to the ComposePanel, but has no public API impact. The
new property is also annotated as experimental.

Author: rock3r

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/awt/ComposePanel.desktop.kt

@@ -23,6 +23,7 @@ import androidx.compose.ui.LayerType
 import androidx.compose.ui.awt.RenderSettings.SkiaSurface
 import androidx.compose.ui.awt.RenderSettings.SwingGraphics
 import androidx.compose.ui.focus.FocusDirection
+import androidx.compose.ui.scene.BaseComposeScene
 import androidx.compose.ui.scene.ComposeContainer
 import androidx.compose.ui.semantics.SemanticsOwner
 import androidx.compose.ui.window.WindowExceptionHandler
@@ -171,7 +172,7 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
 
     override fun getPreferredSize(): Dimension? = if (isPreferredSizeSet) {
         super.getPreferredSize()
-    } else  {
+    } else {
         _composeContainer?.preferredSize ?: Dimension(0, 0)
     }
 
@@ -272,6 +273,7 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
                                     focusManager.takeFocus(FocusDirection.Next)
                                 }
                             }
+
                             else -> Unit
                         }
                     }
@@ -378,4 +380,25 @@ class ComposePanel @ExperimentalComposeUiApi constructor(
     fun renderImmediately() {
         _composeContainer?.renderImmediately()
     }
+
+    @ExperimentalComposeUiApi
+    var showLayoutBounds: Boolean
+        get() {
+            val scene = _composeContainer?.mediator?.scene
+            return if (scene is BaseComposeScene) {
+                scene.showLayoutBounds
+            } else {
+                false
+            }
+        }
+        set(value) {
+            val scene = _composeContainer?.mediator?.scene
+            if (scene is BaseComposeScene) {
+                scene.showLayoutBounds = value
+            } else {
+                error("The scene must be a BaseComposeScene")
+            }
+
+            renderImmediately()
+        }
 }

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/scene/ComposeContainer.desktop.kt

@@ -127,7 +127,7 @@ internal class ComposeContainer(
     private val coroutineExceptionHandler = DesktopCoroutineExceptionHandler()
     private val coroutineContext = MainUIDispatcher + coroutineExceptionHandler
 
-    private val mediator = ComposeSceneMediator(
+    internal val mediator = ComposeSceneMediator(
         container = container,
         windowContext = windowContext,
         exceptionHandler = {

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.desktop.kt

@@ -318,7 +318,7 @@ internal class ComposeSceneMediator(
             }
         }
 
-    private val scene by lazy { composeSceneFactory(this) }
+    internal val scene by lazy { composeSceneFactory(this) }
     val focusManager get() = scene.focusManager
     var compositionLocalContext: CompositionLocalContext?
         get() = scene.compositionLocalContext

compose/ui/ui/src/skikoMain/kotlin/androidx/compose/ui/scene/BaseComposeScene.skiko.kt

@@ -21,7 +21,6 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Composition
 import androidx.compose.runtime.CompositionContext
 import androidx.compose.runtime.CompositionLocalContext
-import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.MonotonicFrameClock
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
@@ -40,8 +39,6 @@ import androidx.compose.ui.input.pointer.PointerType
 import androidx.compose.ui.input.rotary.RotaryScrollEvent
 import androidx.compose.ui.node.SnapshotInvalidationTracker
 import androidx.compose.ui.platform.GlobalSnapshotManager
-import androidx.compose.ui.platform.LocalPlatformScreenReader
-import androidx.compose.ui.platform.LocalPlatformWindowInsets
 import androidx.compose.ui.platform.ProvidePlatformCompositionLocals
 import androidx.compose.ui.util.trace
 import kotlin.concurrent.Volatile
@@ -308,6 +305,8 @@ internal abstract class BaseComposeScene(
     protected abstract fun measureAndLayout()
 
     protected abstract fun draw(canvas: Canvas)
+
+    internal abstract var showLayoutBounds: Boolean
 }
 
 internal val BaseComposeScene.semanticsOwnerListener

compose/ui/ui/src/skikoMain/kotlin/androidx/compose/ui/scene/CanvasLayersComposeScene.skiko.kt

@@ -38,6 +38,7 @@ import androidx.compose.ui.input.pointer.PointerEventType
 import androidx.compose.ui.input.pointer.PointerInputEvent
 import androidx.compose.ui.input.pointer.PointerType
 import androidx.compose.ui.input.rotary.RotaryScrollEvent
+import androidx.compose.ui.node.InternalCoreApi
 import androidx.compose.ui.node.RootNodeOwner
 import androidx.compose.ui.platform.PlatformContext
 import androidx.compose.ui.platform.setContent
@@ -273,6 +274,13 @@ private class CanvasLayersComposeSceneImpl(
         forEachOwner { it.draw(canvas) }
     }
 
+    @OptIn(InternalCoreApi::class)
+    override var showLayoutBounds: Boolean = false
+        set(value) {
+            field = value
+            forEachOwner { it.owner.showLayoutBounds = value }
+        }
+
     /**
      * Find hovered owner for position of first pointer.
      */
@@ -431,6 +439,8 @@ private class CanvasLayersComposeSceneImpl(
 
     private fun onOwnerAppended(owner: RootNodeOwner) {
         semanticsOwnerListener?.onSemanticsOwnerAppended(owner.semanticsOwner)
+        @OptIn(InternalCoreApi::class)
+        owner.owner.showLayoutBounds = showLayoutBounds
     }
 
     private fun onOwnerRemoved(owner: RootNodeOwner) {

compose/ui/ui/src/skikoMain/kotlin/androidx/compose/ui/scene/PlatformLayersComposeScene.skiko.kt

@@ -26,6 +26,7 @@ import androidx.compose.ui.graphics.Canvas
 import androidx.compose.ui.input.key.KeyEvent
 import androidx.compose.ui.input.pointer.PointerInputEvent
 import androidx.compose.ui.input.rotary.RotaryScrollEvent
+import androidx.compose.ui.node.InternalCoreApi
 import androidx.compose.ui.node.LayoutNode
 import androidx.compose.ui.node.RootNodeOwner
 import androidx.compose.ui.platform.setContent
@@ -192,6 +193,13 @@ private class PlatformLayersComposeSceneImpl(
         mainOwner.draw(canvas)
     }
 
+    override var showLayoutBounds: Boolean
+        get() = mainOwner.owner.showLayoutBounds
+        set(value) {
+            @OptIn(InternalCoreApi::class)
+            mainOwner.owner.showLayoutBounds = value
+        }
+
     private fun onOwnerAppended(owner: RootNodeOwner) {
         semanticsOwnerListener?.onSemanticsOwnerAppended(owner.semanticsOwner)
     }